1. Field of the Invention
The invention relates to a method of manufacturing a glass substrate having a plurality of through electrodes and a method of manufacturing electronic components using the same.
2. Background Art
In recent years, piezoelectric vibrators using crystals or the like have been used in a clock source or a timing source of mobile phones or mobile information devices. Various piezoelectric vibrators are known in the art, and a surface-mounted type piezoelectric vibrator is known as one. In addition, a three-layered structure as the piezoelectric vibrator is known in the art, in which a piezoelectric substrate, where a piezoelectric vibrating reed is formed, is vertically interposed and bonded between a base substrate and a lid substrate. The piezoelectric vibrating reed is housed in a cavity formed between the base substrate and the lid substrate.
Furthermore, recently, a two-layered structure piezoelectric vibrator has been developed. This type is formed from a two-layered structure package obtained by directly bonding the base substrate and the lid substrate, and the piezoelectric vibrating reed is housed in the cavity between the base substrate and the lid substrate. The two-layered structure piezoelectric element is advantageous in that it can allow for a lower profile compared to the three-layered structure.
JP-A-2002-124845 and JP-A-2002-121037 disclose a two-layered structure crystal vibrator package, in which a glass material is used as a package material for the base substrate or the lid substrate. The glass material facilitates shaping and reduces manufacturing costs compared to ceramics. In addition, since the glass material has low thermal conductivity, it provides an excellent thermal insulation property, so as to protect an internal piezoelectric vibrator from temperature variation.
JP-A-2003-209198 discloses another two-layered structure crystal vibrator package similar to the aforementioned one. In this case, a glass material is also used in the base substrate, and a method of forming through electrodes using a metal material in the base substrate is disclosed. When the through electrodes are formed in the glass material, first, via-holes are formed in the glass panel. FIGS. 17A and 17B illustrate a method of forming through electrodes including a metal pin 115 in the glass panel 131 (FIG. 3 of JP-A-2003-209198). FIG. 17A illustrates a method of forming a via-hole 119 in the glass panel 131. The glass panel 131 is provided at the bottom of the die 126. The die 126 is provided with a heater 125 so as to heat the glass panel 131. In the upper portion of the die 126, a punch press including a punch 129 is provided. In the glass panel 131 side of the punch 129, perforating pins 128 are provided, and the heater 127 is also provided in the punch 129. In addition, after heating the glass panel 131 to a predetermined temperature, the punch 129 is pressed down to form the via-hole 119.
FIG. 17B illustrates a method of implanting a metal pin 115 in the via-hole 119 of the glass panel 131. The glass panel 131 where the via-hole 119 has been formed is installed in the die 135, and the glass frit 132 is blown into the via-hole 119 using a glass frit blower 133. Then, the metal pin 115 is implanted into the via-hole 119 using a metal pin punch 134.
FIGS. 18A and 18B illustrate a press-molding process (FIG. 4 of JP-A-2003-209198). As shown in FIG. 18A, the glass panel 131 having the metal pin 115 implanted into the via-hole 119 is installed between the lower press template 136 and the upper press template 137. The upper press template 137 is provided with a partitioning convex ridge 138, a pin head hosting recess 139, or a recess-forming convex ridge 141. These templates are placed into an electric furnace and heated to a temperature of 1000° C. or higher while the upper and lower press templates 137 and 136 are pressed to each other. As a result, as shown in FIG. 18B, the engraving on the surface of the upper press template 137 is transferred to the glass panel 131 so that a partitioning trench 142 or a recess 116 is formed in the glass panel 131. At the same time, through electrodes including the metal pin 115 having a hermetical sealing property are formed in the glass panel 131.
However, if the glass panel 131 is heated, the via-hole 119 is formed, and then, the glass panel 131 is cooled, the glass panel 131 is distorted due to internal stress, and the flatness of the glass panel 131 is degraded. In addition, if the cooling is performed after the surface engraving of the upper press template 137 is transferred to the glass panel 131, some problems may occur. For example, the metal pin 115 may be slanted, or positioning of the metal pin 115 may be deviated due to flow of glass during the transfer or irregular heat distribution during the cooling. In addition, the glass panel 131 may be complexly distorted due to internal stress. If the bending is to be corrected through grinding, the amount of grinding may become significant, and much time may be necessary in the fabrication. In addition, the number of parts having a predetermined shape may be reduced. Furthermore, the metal pin 115 exposed on the bottom of the recess 116 is slanted, so that the positions of the through electrodes may be deviated. If the flatness of the top surface of the side wall surrounding the recess 116 is not excellent, the hermetical sealing property of the lid joining with the top surface may not be guaranteed. This may reduce reliability of an electronic component.